Fuse for hand grenades



June 20, 1950 E. M. SHlNKLE FUSE FOR HAND GRENADES Filed Jan. 30, 1948 llli INVEN TOR. fame!) M. jfi/MCAE ATTOEWEXF Patented June 20, 1950 2,512,179 Fuss Fora HAND GRENADES Edward M. Shinkle, SanFranciscmCalif. Application January 30, 1948 Serial No. 5,401 3 Claims. (01. in -81.6)

This invention relates to a fuse, and more particularly to a fuse for a hand grenade which is actuated by percussion.

In general, grenades are provided with time or dela fuses, which are set in operation by the thrower of the grenade. In the usual type of time or delay fuse, a lever or handle is released to initiate operation of the fuse mechanism. Among thedisadvantages of this type of mechanism is the fact that a certain definite interval of time must elapse after the lever handle has been released before the grenade explodes. Thus, it is frequently possible for the enemy to pick up the grenade after it has landed, and to throw it back or otherwise dispose of it. If the thrower holds the grenade after releasing the lever or handle, there is a considerable danger that a faulty fuse mechanism will detonate the grenade while it is still in the hands of or close to the thrower.

In my Patent No. 2,408,486, entitled Hand Grenade and Fuse Therefor, granted October 1, 1946, there is described and claimed a hand grenade fuse which is actuated by percussion or shock. In this structure there is provided a glass ampule containing chemicals. The ampule breaks upon impact, as when the grenade is thrown and strikes a solid object. The breakage of the ampule and consequent release of the chemicals initiates a chemical reaction, which evolves sumcient heat to ignite the primer, which in turn causes detonation of the grenade.

It is an object of the present invention to provide a fuse for a hand grenade which is actuated by percussion, yet obviates the necessity of using chemicals and does not require the use of a fragile container, such as a glass ampule.

It is a further object of the invention to. provide a fuse for a hand grenade, which is actuated by percussion or shock and which is entirely mechanical in its operation.

These and other objects of the invention will be apparent from the ensuing description and the appended claims.

The invention will be better understood by reference to the accompanying drawings, in which:

Fig. 1 is a vertical mid-section through a grenade containing the fuse of the invention in its preferred form.

Fig. 2 is a horizontal cross-section taken along the line 2-2 of Fig. 1, but with the retainer element removed.

Fig. 3 is a perspective view of one of thesupporting legs. used to support the firing pin, show 2 ing also construction lines to clarify the configuration of the supporting leg.

Referring now to the figures of the drawings, and more particularl to Fig. 1, there is shown a grenade I comprising a body portion 2 and a fuse 3. The body 2 is provided with ribs 4, a bottom plug 5 in threaded engagement with a bottom opening 6, and an upper threaded opening 7'. The interior of the body, externally of the fuse 3, is filled with an explosive 8. These elements of the grenade body and the filling of explosive are conventional in the art and are shown, for example, in my above mentioned Patent No. 2,408,486.

The fuse 3 comprises a tubular housing provided at about its mid-portion with an annular shelf or transom it having a central opening 11. The tubular housing l5 may be constructed in any suitable manner. Thus, it may be constructed of an upper section Ida having the shelf 16' as a bottom closure, and a lower sec tion [5b in threaded engagement with the upper section at Ill, as shown. The upper portion of the housing [5 is threaded at E3 to engage the threaded upper opening I- of the grenade body, and it is also provided with an annular flange as which bears against a gasket at to securely seal the opening I. The lower portion of the housing is threaded to receive a threaded primer plug 2| and the lower portion of the primer plug is provided with a threaded recess 22 to receive a threaded detonator'plug 23-. A primer 2:: of any suitable material is provided in a recess 25 in the primer plug,'and a suitable detonator 25, such as f-ulminate of mercury, lead azide, or the like, is

provided in a recess 21 in the detonator plug, as shown. An opening 28 in the primer plug is provided to'facilitate ignition of the detonator.

The firing. mechanism comprises a firing pin 30- having a pointed tip 3| and an enlarged, conical head 32. The pin is supported by three supporting legs 33 bearing against the conical head and is urged downwardly toward the primer by a spring 34 compressed between the shelf I6 and a bearing. washer 35,. which is secured to the firing pin by a pin 36 or othersuitable means.

Referring now more particularly to Figs. 2 and 3;. each supporting leg 33 is a generally triangular structure having abase 45), two sides M, an inner face 42, an outer face 43 and an apex 44. As shown'more clearly in Fig. 3, with the aid of the construction lines, the sides M widen as they approach the apex M, the base 40 forms an acute angle with the outer face 43- and the apex 44 slantsdownwardly'from the outer facev 43 to the inner face 42. The base and the apex 44 are narrow, as shown, so as to present a minimum of bearing surface for a purpose hereinafter described.

As shown more clearly in Fig. 2, three supporting legs 33 are arranged equi-angularly around the firing pin 30, with their bases 40 forming 120 chords of the circle 46 defined by the interior circumference of the fuse housing l5, and their apexes 44 bearing against elements of the conical head 32 of the firing pin.

It will be seen that the supporting legs 33 provide support for the firing pin to prevent its being urged by the spring 34 into contact with the primer 24. However, this support is purposely somewhat delicate and collapses whenever it receives a sharp mechanical shock, as when the grenade is thrown and strikes a solid surface.

Thus, a balanced support of the firing pin 30 is achieved, which safely supports the pin in nonfiring position as long as the grenade is in the hands of the thrower or is in flight, but which collapses and causes. the pin to fire the primer when the grenade strikes a solid object with considerable force, as when it falls upon the ground. 9

This balanced support is achieved by the symmetrical support .provided by the legs 33, and by the limited bearing surfaces of the bases 40 and the apexes 44 of the legs, which bear against the shelf I6 and walls of the housing l5, and against the conical head 32, respectively.

The most advantageous balance for the firing pin 30 is achieved, with a modicum of trial and error, by observing the following conditions: The inclination of each supporting leg 33, identified as a in Fig. 3, and the slope of the conical head 32 (hence, also, the inclination of the apex 44), should be such that the line of thrust of the conical head against the legs makes an angle 0 with the adjacent conic element, of less than 90. The deviation of 0 from 90 will lie between 0 and the angle of friction between the materials involved, andthe optimum value of 0 will lie somewhere in this range. The closer 0 approaches 90, the more stable the support, and the farther it deviates from 90. the less stable the support. An intermediate, optimum angle providing the proper stability during handling, but unstable against sudden mechanical shock, can be determined by trial and error.

Auxiliary support for the firing pin 30, to provide safety in transporting, handling and throwing the grenade, is provided by means of a retainer generally designated as 50. The retainer comprises a head portion 5| having an annular flange 52 which bears against the fuse housing, as shown, and a tubular sleeve 53 depending from the underside of the head portion a sufiicient distance to encircle the conical head 32 of the firing pin and to bear against and encircle the upper portions of the supporting legs 33. To .provide a loose sliding fit adapted to hold the legs 33 securely in place but also to facilitate ejection of the retainer 50 in the manner hereinafter described, the inner surface of the sleeve 53 is given a slight outward and downward taper at 59 and each leg 33 is provided with a circular boss or extension having a complemental taper.

A spring 54 is compressed between the head portion 5| of the retainer and the conical head 32 of the firing pin. The spring 54 thus acts to eject the retainer 50 from the fuse housing. A transverse pin 55 extending through complemental bores 56 and-51 in the head portion of the retainer and the flanges IQ of the fuse housing,:

4 respectively, locks the retainer 50 in supporting position until the pin 55 is pulled out. A ring 58 secured to one end of the pin 55 provides a means of pulling out the pin.

It will be seen that, as long as the firing pin 30 is supported by the legs 33 and as long as auxiliary support is provided by the tubular sleeve 53, the firing pin is held firmly in non-firing position. When, however, the pin 55 is removed, the spring 54 will immediately eject the retainer 50, thus removing the auxiliary support for the supporting legs. After ejection of the retainer 50, the firing pin is supported only by the supporting legs 33, which, as stated, are adequate to support the firing pin in non-firing position while the grenade is in the hands of the thrower and during flight. When the grenade strikes a solid object, thus receiving a sudden mechanical shock, one or more of the supporting legs will become dislodged, with resulting collapse of support of the firing pin. The firing pin is then urged downwardly by thespring 34 into contact with the primer 24, thus causing ignition of primer and detonation of the grenade.

In using the grenade, and with the various parts assembled as shown in Fig. 1, the thrower will grasp the grenade with his thumb or a finger firmly over the head portion of the retainer 50. With his free hand, the thrower will then grasp the ring 58 and remove the pin 55. Still keeping his thumb or finger on the head portion, he will then throw the grenade. As soon as the grenade is in flight, the spring 54 will eject the retainer 50, thus removing the auxiliary support for the legs 33. When the grenadehas reached the end of its flight and has struck a solid object, the resulting suddenmechanical shock will, as above mentioned, unbalance the support for the firing pin, resulting in release of the latter and detonation or explosion of the grenade.

The fuse-thus described is also adapted to use as a'time or delayed fuse. Thus, a compressed charge of black powder or other suitable slow burning substance (not shown) may be inserted in the fuse, intermediate the primer 24 and the detonator 26. Or, where a low explosive is employed which does notrequire detonation, the detonator 26 may be omitted altogether.

Moreover, it will beapparent that the structure of the invention has broader applicability than as a fuse for a grenade. Thus, it can be used as a: fuse for any type ofv explosive device, such as a land mine, provided only that the explosive devicelis intended to be subjected to mechanical shock as the means of detonation. Also, the principle of. the invention, and its embodiment in a pin urged by a spring or the like toward a target or objective and restrained by a balanced, delicate support, and also'by a more stable support which' can be disengaged, is applicable to mechanisms of entirely different character. For example, this'structure may be used to set and actuate an animal trap.

While I have shown the preferred form of my invention, it is to be understood that various changesmay be made in its construction by those skilled in the art without departing from the spirit of the invention as defined in the appended claims.

Having thus described my invention-what I claim and desire to obtain by Letters Patent is:

l.'A fuseScQmprising a tubular housing pro-' vided at its mid-portion with an annular shelf, said shelf being provided with a central opening, a firing pin havinga'conical headiand sup-j ported within said housing and extending through said opening, a spring urging said pin to firing position, a plurality of legs, each supported at its lower end by said shelf and bearing at its upper end against said conical head, the said legs providing support for said pin in nonfiring position except against sudden mechanical shock, an auxiliary support comprising a tubular sleeve covering said conical head and bearing against the upper portions of said legs to support the same against suddent mechanical shock, a spring urging said auxiliary support outwardly of said housing and out of contact with said legs, and removable means for locking said auxiliar support in supporting position.

2. The fuse of claim 1, wherein said legs are three in number, each comprising a triangular block having a base forming a 120 chord with said tubular housing, and each leg also comprising a thin, inwardly and downwardly slanting apex bearing against an element of said conical head.

3. A fuse comprising a tubular fuse housing; a closure at the lower end thereof providing means for receiving and retaining a primer charge; an annular shelf extending inwardly from the interior walls of said housing and provided with a central opening; a firing pin having a conical head and supported longitudinally of said housing and extending through said opening with its conical head thereabove; a spring encircling said pin and compressed between the underside of said shelf and the lower end of said pin 50 as to urge the pin to firing position; three supporting legs, each in the form of a triangular block having a base resting upon said shelf and forming a 120 chord with said housing, and having a thin, inwardly and downwardly slanting apex bearing against an element of said conical head; and an auxiliary support acting to support said legs against mechanical shock, comprising a head portion, removable means looking said head portion in supporting position, a spring compressed between the underside of said head portion and the top of said conical head, and a tubular sleeve depending from said head portion, encircling said conical head and bearing against said legs.

EDWARD M. SHINKLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,339,735 Bergman May 11, 1920 2,375,522 Campbell May 8, 1945 FOREIGN PATENTS Number Country Date 126,041 Great Britain May 8, 1919 49,984 Sweden Aug. 31, 1921 317,577 Italy May 16, 1934 

